A composite fiber for sanitary products and a method for producing the same

Abstract

The present application relates to the technical fields of composite fiber and sanitary material, and discloses a kind of composite fiber for sanitary product and preparation method thereof, the composite fiber is sheath-core type two-component structure, core layer is mainly with polyethylene terephthalate, skin layer is composed of polyethylene and maleic anhydride grafted polyethylene, and the surface of skin layer is provided with functional layer formed by quaternary ammonium cyclodextrin composite material, silane-based auxiliary agent, polyethylene glycol, glycerol and non-ionic surfactant.The preparation is carried out by two-component melt spinning, drawing heat setting, then coated with functional coating liquid and heat treated.The present application utilizes maleic anhydride grafted polyethylene and silane-based auxiliary agent to enhance the interfacial bonding of functional layer on the surface of polyethylene skin layer, so that the obtained fiber has the properties of persistent hydrophilicity, repeated infiltration stability and antibacterial performance, and is suitable for sanitary napkin, paper diaper and medical disposable sanitary material.

Description

Technical Field

[0001] This invention relates to the field of composite fiber and sanitary materials technology, specifically to a composite fiber for sanitary products and its preparation method. Background Technology

[0002] Sanitary napkins, baby diapers, adult incontinence products, and disposable medical hygiene products typically consist of a top layer, a distribution layer, an absorbent core, and a leak-proof bottom layer. The top and distribution layers directly affect the rate of liquid penetration, lateral diffusion, backflow resistance, and the feel against the skin during use. To balance fiber softness, thermal bonding properties, and mechanical properties, nonwoven fabrics used in hygiene products often employ polyethylene / polyethylene terephthalate (PET) sheath-core bicomponent fibers. These fibers use low-melting-point polyethylene as the sheath and high-melting-point PET as the core, with the sheath melting during hot air or hot rolling to form bonding points between the fibers.

[0003] However, polyethylene itself is a non-polar polymer material with low surface energy and poor natural hydrophilicity. To meet the requirements of rapid absorption and permeation of liquids in hygiene products, hydrophilic oils or hydrophilic finishing agents are usually applied to the fiber surface after spinning. Traditional hydrophilic finishing agents mainly rely on physical adsorption to adhere to the polyethylene surface. During fiber storage, transportation, nonwoven fabric processing, and actual contact with liquids such as urine and menstrual blood, the finishing agent is prone to migration, shedding, or redistribution, resulting in a decrease in the fiber's hydrophilicity. Especially under conditions of continuous liquid permeation, its permeability is easily and significantly reduced in the second, third, and subsequent permeation stages.

[0004] Furthermore, some existing technologies improve the initial hydrophilicity of fibers by increasing the amount of surface finishing agents. However, excessive amounts of finishing agents can easily cause the fiber surface to become sticky, reduce fiber openness, and decrease the processing performance of nonwoven fabrics, and may also increase oil migration and skin contact residue. Therefore, simply increasing the amount of hydrophilic finishing agents is insufficient to simultaneously achieve hydrophilic durability, softness, processing stability, and skin friendliness. Therefore, there is a need to develop a composite fiber for hygiene products and its preparation method that, while maintaining the softness, bulkiness, and thermal bonding properties of PE / PET bicomponent fibers, improves the interfacial bonding strength between the functional finishing layer and the fiber sheath, and further endows the fiber with durable hydrophilicity and antibacterial functions. This would address the problems of easy migration of hydrophilic finishing agents, decreased performance with repeated seepage, and insufficient durability of the functional layer in existing hygiene product fibers. Summary of the Invention

[0005] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a composite fiber for hygiene products and its preparation method. By introducing maleic anhydride-grafted polyethylene into the polyethylene sheath to enhance interfacial reactivity, and constructing a functional layer containing quaternized cyclodextrin composite material and silane additives on the fiber surface, the bonding stability between the functional finishing layer and the sheath is improved, thereby achieving long-lasting hydrophilic and antibacterial functions.

[0006] Technical solution To achieve the above objectives, the present invention provides the following technical solution: A composite fiber for hygiene products comprises the following raw materials in parts by weight: the composite fiber is composed of a core layer, a sheath layer, and a functional coating liquid; The core layer comprises 90-100 parts of polyethylene terephthalate; The skin layer comprises polyethylene and maleic anhydride-grafted polyethylene, and by weight, the skin layer consists of 94 to 98 parts of polyethylene and 2 to 6 parts of maleic anhydride-grafted polyethylene. The functional coating liquid comprises the following components: 1-2 parts of quaternized cyclodextrin composite material; 1-3 parts of silane additive; 2-4 parts polyethylene glycol; Glycerin 0.1-0.5 parts; Nonionic surfactant: 0.1–0.3 parts; 15-25 parts ethanol; 75-85 parts deionized water.

[0007] Furthermore, the polyethylene terephthalate serves as the main load-bearing component of the fiber, maintaining the mechanical strength and dimensional stability of the composite fiber; the polyethylene forms a skin layer to improve the fiber's softness and thermal bonding properties; the maleic anhydride-grafted polyethylene is dispersed in the polyethylene skin layer, and the polar maleic anhydride groups in its molecular chain are used to improve the interfacial bonding ability between the non-polar polyethylene skin layer and the functional coating layer.

[0008] Furthermore, the preparation method of the silane-based additive is as follows: S1. Vanillin and glycerol triglycidyl ether were added to a reaction flask and heated to 100-110°C under a nitrogen atmosphere. The mixture was stirred until homogeneous. Then, 4-dimethylaminopyridine catalyst was added and the reaction was carried out under magnetic stirring for 2-4 hours. After the reaction was completed, the trialdehyde precursor was obtained. S2. Add octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide to the reaction flask. Under nitrogen protection, stir and heat the mixture to 90°C and react for 4 hours. Then raise the temperature to 140°C and continue the reaction for 1 hour to deactivate the catalyst. Then, use a vacuum pump to evacuate the vacuum and remove unreacted raw materials and low-boiling substances by vacuum distillation to obtain diaminopropyl-terminated polysiloxane. S3. Add trialdehyde precursor and diaminopropyl-terminated polysiloxane to N,N-dimethylformamide solvent, stir and mix, react at 65-75℃ for 6-10h, distill under reduced pressure and dry under vacuum to obtain silane additive.

[0009] Furthermore, the silane additive is an organosilicon functional additive that simultaneously contains polysiloxane segments, aromatic aldehyde-derived structures, and Schiff base bonds; the polysiloxane segments are used to improve the flexibility and surface smoothness of the functional coating layer, and the aromatic structure and Schiff base structure are used to enhance the intermolecular interaction between the silane additive and the quaternized cyclodextrin composite material, so that the functional components are stably attached to the surface of the fiber sheath.

[0010] Further, in step S1, the ratio of vanillin, glycerol triglycidyl ether, and 4-dimethylaminopyridine catalyst is 20.2-22.9g: 21.1-23.4g: 0.41-0.45g.

[0011] Further, in step S2, the ratio of octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and tetramethylammonium hydroxide is 24-25.8g: 24.7-25.4g: 1.31-1.36g.

[0012] Furthermore, in step S3, the trialdehyde precursor and the diaminopropyl-terminated polysiloxane are mixed and reacted to achieve a molar ratio of aldehyde to amino groups of 1:1.

[0013] Furthermore, the method for preparing the composite fiber for hygiene products is as follows: A1. Polyethylene terephthalate is vacuum dried at 120-140℃ for 4-6 hours to obtain the core layer material; polyethylene and maleic anhydride-grafted polyethylene are dried at 60-80℃ for 2-4 hours according to the weight ratio, and then mixed at 500-800r / min for 10-20 minutes to obtain the skin layer material. A2. The core material and the sheath material are fed into a bicomponent melt spinning device, wherein the melting temperature of the core material is 270-285°C and the melting temperature of the sheath material is 180-210°C. They are then transported by a metering pump to a core-sheath bicomponent spinning assembly for compounding and extrusion through a spinneret. The extruded material is then cooled and shaped at 18-25°C to obtain core-sheath nascent fiber. A3. The core-sheath type nascent fiber is stretched by 2.5 to 3.5 times at 70 to 90°C, and then heat-set at 100 to 120°C to obtain a core-sheath type bicomponent matrix fiber. A4. Add the quaternized cyclodextrin composite material, silane additive, polyethylene glycol, glycerol and nonionic surfactant to a mixed solvent composed of ethanol and deionized water according to the weight parts, stir at 600-1000 r / min for 20-40 min, and then ultrasonically disperse at 200-400 W for 15-30 min to obtain a uniform functional coating liquid. A5. The functional coating liquid is uniformly coated onto the surface of the core-sheath bicomponent matrix fiber, dried at 60-80°C for 3-8 minutes, then heat-treated at 105-120°C for 1-3 minutes, and cooled to obtain composite fiber for hygiene products.

[0014] Furthermore, in step A3, the setting time is 60–90 seconds.

[0015] Furthermore, in step A5, the dry basis adhesion amount of the functional coating liquid is 1.0 to 3.0% of the mass of the core-sheath type bicomponent matrix fiber.

[0016] Beneficial technical effects This invention uses polyethylene terephthalate as the core layer and polyethylene and maleic anhydride-grafted polyethylene as the sheath layer to form a core-sheath type bicomponent composite fiber. While maintaining the fiber's good mechanical strength, dimensional stability, softness and thermal bonding performance, the polar groups contained in maleic anhydride-grafted polyethylene are used to improve the interfacial activity of the polyethylene sheath layer and enhance the bonding ability between the sheath layer and the surface functional coating layer. This reduces the migration and shedding of functional components during storage, processing and repeated contact with liquids, and improves the adhesion stability and durability of the functional layer.

[0017] This invention constructs a functional layer on the fiber surface containing a quaternized cyclodextrin composite material, a silane additive, polyethylene glycol, glycerol, and a nonionic surfactant. The components work synergistically to improve the wettability of the fiber surface, promote rapid liquid wetting and penetration, and slow the loss of hydrophilic components after repeated liquid interactions, giving the composite fiber good long-lasting hydrophilicity and repeated penetration stability. Simultaneously, the quaternized cyclodextrin composite material imparts certain antibacterial properties to the fiber, resulting in a composite fiber with both hydrophilic and antibacterial functions.

[0018] Furthermore, the polysiloxane segments contained in the silane additives help improve the flexibility and surface smoothness of the functional coating layer, while the aromatic and Schiff base structures enhance the intermolecular interactions between the additives and the quaternized cyclodextrin composite material, thereby further improving the stable adhesion of the functional components to the fiber surface. This invention can produce the target composite fiber through bicomponent melt spinning, stretching and heat setting, functional coating, and heat treatment. The process conditions are well-defined and easy to control, effectively balancing the fiber's processing and performance characteristics. It is suitable for applications such as sanitary napkins, diapers, and disposable medical hygiene materials. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of composite fibers used in hygiene products.

[0021] 1-PET core layer; 2-PE / maleic anhydride grafted polyethylene skin; 3-Functional coating layer. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Polyethylene terephthalate (PET), fiber-grade PET chips, Sinopec Yizheng Chemical Fiber Co., Ltd.; the polyethylene is fiber-grade polyethylene, grade ASPUN™ 6835A FiberResin, manufactured by Dow Chemical; maleic anhydride-grafted polyethylene (PE-g-MAH), maleic anhydride grafting rate 0.8-1.2%; polyethylene glycol (PEG-400), analytical grade, Sinopharm Chemical Reagent Co., Ltd.; nonionic surfactant: polysorbate 20.

[0024] Preparation of quaternized cyclodextrin composite materials, reference: Wang Xin, "Preparation and Adsorption / Antibacterial Properties Study of Quaternized Cyclodextrin Composite Materials", Master's Thesis, Resources and Environment, Water Pollution Control Technology, East China University of Science and Technology, May 2023; specifically: Add 4g of CS (chitosan) to 50mL of 1% acetic acid solution and leave overnight to completely dissolve CS. Then, add 8g of CD-CA (citric acid cross-linked cyclodextrin) to the above solution and transfer to a round-bottom flask. Heat in an oil bath at 130℃ for 2-4 hours. Cool the reaction mixture to room temperature and add 200mL of NaOH solution to precipitate the grafted product. Wash with deionized water and anhydrous ethanol alternately 3-5 times to obtain CD-CA-CS for later use.

[0025] The cyclodextrin composite material (CD-CA-CS) was added to 50 mL of 1% acetic acid solution and left overnight to dissolve completely. Then, glycidyltrimethylammonium chloride (GTAC) was added, with a mass ratio of GTAC to CD-CA of 1:1. The mixture was heated in an oil bath at 55 °C for 22 h to obtain the quaternized cyclodextrin composite material.

[0026] Example 1

[0027] A method for preparing composite fibers for hygiene products specifically includes the following steps: (1) Preparation of silane-based additives: 20.2 g vanillin and 21.1 g glycerol triglycidyl ether were added to a reaction flask and heated to 100 °C under nitrogen protection. After stirring and mixing, 0.41 g 4-dimethylaminopyridine was added and reacted for 2 h to obtain a trialdehyde precursor. Separately, 24.0 g octamethylcyclotetrasiloxane, 24.7 g 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1.31 g tetramethylammonium hydroxide were mixed and reacted at 90 °C for 4 h under nitrogen protection, and then the temperature was increased to 140 °C for 1 h. Unreacted raw materials and low-boiling substances were removed under reduced pressure to obtain diaminopropyl-terminated polysiloxane. A trialdehyde precursor and a diaminopropyl-terminated polysiloxane were added to 100 mL of N,N-dimethylformamide at a theoretical molar ratio of aldehyde to amino of 1:1. The mixture was reacted at 65 °C for 6 h, the solvent was removed under reduced pressure, and the mixture was dried under vacuum at 60 °C for 12 h to obtain a silane-based additive.

[0028] (2) Take 90 parts of fiber-grade PET and vacuum dry at 120℃ for 6h as core material; take 94 parts of polyethylene and 6 parts of maleic anhydride-grafted polyethylene and dry at 60℃ for 4h, and mix at 500r / min for 20min to obtain skin material.

[0029] (3) The core material and the sheath material are fed into the bicomponent melt spinning device respectively. The core melting temperature is 270℃ and the sheath melting temperature is 180℃. They are transported to the sheath-core bicomponent spinning assembly for composite by metering pump, extruded by spinneret and cooled and shaped under 18℃ cooling air to obtain sheath-core nascent fiber.

[0030] (4) The nascent fiber is stretched 2.5 times at 70°C and then heat-set at 100°C for 90s to obtain a core-sheath bicomponent matrix fiber.

[0031] (5) Add 1.0 part of quaternized cyclodextrin composite material, 1.0 part of silane additive, 2.0 part of PEG-400, 0.1 part of glycerol and 0.1 part of polysorbate 20 to a mixed solvent consisting of 15 parts of ethanol and 75 parts of deionized water, stir at 600 r / min for 40 min, and then ultrasonically disperse at 200 W for 30 min to obtain the functional coating liquid.

[0032] (6) The functional coating liquid is uniformly coated on the surface of the matrix fiber so that the dry base adhesion amount is 1.0% of the matrix fiber mass. It is dried at 60℃ for 8 minutes, then heat-treated at 105℃ for 3 minutes, and cooled to obtain composite fiber for hygiene products.

[0033] Use composite fibers.

[0034] Example 2

[0035] A method for preparing composite fibers for hygiene products specifically includes the following steps: (1) Preparation of silane-based additives: 21.5 g vanillin, 22.2 g glycerol triglycidyl ether and 0.43 g 4-dimethylaminopyridine were reacted at 105 °C for 3 h under nitrogen protection to obtain a trialdehyde precursor; 24.9 g octamethylcyclotetrasiloxane, 25.0 g 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1.34 g tetramethylammonium hydroxide were reacted at 90 °C for 4 h under nitrogen protection, then reacted at 140 °C for 1 h and the low-boiling point was removed under reduced pressure to obtain diaminopropyl-terminated polysiloxane. The two were added to 100 mL of N,N-dimethylformamide at a theoretical molar ratio of aldehyde to amino of 1:1, reacted at 70 °C for 8 h, the solvent was removed under reduced pressure and the mixture was dried under vacuum at 60 °C for 12 h to obtain silane-based additives.

[0036] (2) Take 95 parts of fiber grade PET and vacuum dry at 130℃ for 5h; take 96 parts of polyethylene and 4 parts of maleic anhydride grafted polyethylene and dry at 70℃ for 3h, and mix at 650r / min for 15min.

[0037] (3) The core melting temperature is controlled at 278℃ and the sheath melting temperature is controlled at 195℃. The core-sheath type nascent fiber is obtained under the cooling air condition of 22℃.

[0038] (4) The nascent fiber was stretched 3.0 times at 80°C and then heat-set at 110°C for 75s to obtain a core-sheath bicomponent matrix fiber.

[0039] (5) Add 1.5 parts of quaternized cyclodextrin composite material, 2.0 parts of silane additive, 3.0 parts of PEG-400, 0.3 parts of glycerol and 0.2 parts of polysorbate 20 to a mixed solvent consisting of 20 parts of ethanol and 80 parts of deionized water. Stir at 800 r / min for 30 min and then ultrasonically disperse at 300 W for 20 min to obtain the functional coating liquid.

[0040] 6) The functional coating liquid is evenly coated on the surface of the base fiber so that the dry base adhesion is 2.0%, dried at 70℃ for 5 min, then heat-treated at 112℃ for 2 min, and cooled to obtain composite fiber for hygiene products.

[0041] Example 3 A method for preparing composite fibers for hygiene products specifically includes the following steps: (1) Preparation of silane-based additives: 22.9 g vanillin, 23.4 g glycerol triglycidyl ether and 0.45 g 4-dimethylaminopyridine were reacted at 110 °C for 4 h under nitrogen protection to obtain a trialdehyde precursor; 25.8 g octamethylcyclotetrasiloxane, 25.4 g 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and 1.36 g tetramethylammonium hydroxide were reacted at 90 °C for 4 h under nitrogen protection, then reacted at 140 °C for 1 h and the low-boiling substances were removed under reduced pressure to obtain diaminopropyl-terminated polysiloxane. The two were added to 100 mL of N,N-dimethylformamide at a theoretical molar ratio of aldehyde to amino of 1:1, reacted at 75 °C for 10 h, the solvent was removed under reduced pressure and the mixture was dried under vacuum at 60 °C for 12 h to obtain silane-based additives.

[0042] (2) Take 100 parts of fiber grade PET and vacuum dry at 140℃ for 4h; take 98 parts of polyethylene and 2 parts of maleic anhydride grafted polyethylene and dry at 80℃ for 2h, and mix at 800r / min for 10min.

[0043] (3) The core melting temperature is controlled at 285℃ and the sheath melting temperature is controlled at 210℃. Core-sheath type nascent fiber is obtained under a cooling air condition of 25℃.

[0044] (4) The nascent fiber was stretched 3.5 times at 90°C and then heat-set at 120°C for 60s to obtain a core-sheath bicomponent matrix fiber.

[0045] (5) Add 2.0 parts of quaternized cyclodextrin composite material, 3.0 parts of silane additive, 4.0 parts of PEG-400, 0.5 parts of glycerol and 0.3 parts of polysorbate 20 to a mixed solvent consisting of 25 parts of ethanol and 85 parts of deionized water, stir at 1000 r / min for 20 min, and then ultrasonically disperse at 400 W for 15 min to obtain the functional coating liquid.

[0046] (6) The functional coating liquid is uniformly coated on the surface of the base fiber so that the dry base adhesion amount is 3.0%, dried at 80°C for 3 min, then heat-treated at 120°C for 1 min, and cooled to obtain composite fiber for hygiene products.

[0047] Comparative Example 1 The difference between this comparative example and Example 2 is that maleic anhydride-grafted polyethylene is not added to the skin material, and the skin material is adjusted to 100 parts of polyethylene, that is, pure polyethylene is used as the skin material; the remaining raw material amounts, silane additive preparation methods, two-component melt spinning conditions, stretching and heat setting conditions, functional coating liquid composition, coating process and heat treatment conditions are the same as in Example 2.

[0048] Comparative Example 2 The difference between this comparative example and Example 2 is that the amount of maleic anhydride-grafted polyethylene in the skin material is reduced from 4 parts to 1 part, and the amount of polyethylene is adjusted accordingly to 99 parts; the amount of other raw materials and the preparation steps are the same as in Example 2.

[0049] Comparative Example 3 The difference between this comparative example and Example 2 is that the amount of quaternized cyclodextrin composite material in the functional coating liquid is reduced from 1.5 parts to 0.5 parts; the amount of other raw materials and the preparation steps are the same as in Example 2.

[0050] Comparative Example 4 The difference between this comparative example and Example 2 is that the silane additive prepared in Example 2 is replaced with an equal mass of γ-aminopropyltriethoxysilane (KH-550), and the amount added is still 2.0 parts; the other functional coating liquid components, bicomponent fiber composition and preparation conditions are the same as in Example 2.

[0051] Comparative Example 5 The dry basis adhesion of the functional coating liquid on the surface of the core-sheath bicomponent matrix fiber was reduced from 2.0% to 0.5%; the composition of the functional coating liquid and the remaining spinning, drawing, heat setting, drying and heat treatment conditions were the same as in Example 2.

[0052] The performance of the composite fibers for hygiene products prepared in the examples and comparative examples is now being tested. The specific test methods are as follows: 1. Hydrophilic properties (sinking time) FZ / T50040-2018 Test Method for Hydrophilic Properties of Chemical Fibers (Short Fibers) 2. Liquid penetration time (GB / T24218.13-2010 "Textiles - Nonwovens - Test Methods - Part 13: Determination of Liquid Penetration Time") 3. Moisture Reabsorption Rate GB / T24218.14-2010 "Textiles - Test Methods for Nonwovens - Part 14: Determination of Moisture Reabsorption Rate of Covering Materials" 4. Antibacterial properties GB / T20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Vibration method" 5. Tensile strength GB / T14337-2022 "Test Method for Tensile Properties of Chemical Fibers (Short Fibers)".

[0053] Table 1: Hydrophilicity and Repeated Liquid Penetration Performance Tests Sample Sinking time / s First penetration time / s Second penetration time / s 3rd penetration time / s Re-humidification amount / g Example 1 1.48 2.31 2.42 2.68 0.13 Example 2 1.39 2.34 2.51 2.81 0.15 Example 3 1.55 2.26 2.44 2.94 0.14 Comparative Example 1 1.71 2.39 3.26 4.48 0.27 Comparative Example 2 1.65 2.38 2.88 3.46 0.22 Comparative Example 3 1.81 2.52 2.75 3.03 0.18 Comparative Example 4 1.66 2.43 2.95 3.61 0.23 Comparative Example 5 2.43 3.01 3.45 3.91 0.30 Table 2: Antibacterial and Mechanical Properties Tests Sample Staphylococcus aureus inhibition rate / % Escherichia coli inhibition rate / % Fracture strength / (cN / dtex) Example 1 92.1 90.3 3.31 Example 2 94.4 92.7 3.28 Example 3 95.6 94.0 3.25 Comparative Example 1 86.4 83.6 3.35 Comparative Example 2 88.0 86.5 3.30 Comparative Example 3 73.6 70.8 3.32 Comparative Example 4 82.5 87.6 3.27 Comparative Example 5 78.8 75.6 3.33 As shown in Tables 1 and 2, Comparative Example 1, based on Example 2, omits maleic anhydride-grafted polyethylene and uses only 100 parts of polyethylene as the skin layer. Its first liquid penetration time was 2.39 s, close to 2.34 s in Example 2, but the second and third times were extended to 3.26 s and 4.48 s, respectively. The amount of rewetting increased from 0.15 g to 0.27 g; the inhibition rates against Staphylococcus aureus and Escherichia coli also decreased from 94.4% and 92.7% to 86.4% and 83.6%, respectively. This indicates that maleic anhydride-grafted polyethylene does not primarily improve initial wetting, but rather enhances the interfacial polarity of the PE skin layer and the adhesion stability of the functional layer, reducing the migration and shedding of functional components during repeated liquid interactions and oscillation tests. Therefore, maintaining its long-lasting hydrophilicity and antibacterial properties is more crucial.

[0054] Comparative Example 2 reduced the amount of maleic anhydride-grafted polyethylene from 4 parts to 1 part. Its third liquid penetration time was 3.46 s and rewetting amount was 0.22 g, both significantly worse than 2.81 s and 0.15 g in Example 2, but better than 4.48 s and 0.27 g in Comparative Example 1. The inhibition rates of the two bacteria were 88.0% and 86.5%, respectively, also falling between those of Example 2 and Comparative Example 1. The data show a clear gradient relationship, indicating that while 1 part of maleic anhydride-grafted polyethylene can produce a certain interface reinforcement effect, it is insufficient to achieve the functional layer stabilization effect of 4 parts.

[0055] In Comparative Example 3, when the amount of quaternized cyclodextrin composite material was reduced from 1.5 parts to 0.5 parts, the inhibition rates of Staphylococcus aureus and Escherichia coli significantly decreased from 94.4% and 92.7% in Example 2 to 73.6% and 70.8%, respectively, making it the group with the most significant decrease in antibacterial activity among the single-factor comparative examples. The settling time increased from 1.39 s to 1.81 s, the third liquid penetration time increased from 2.81 s to 3.03 s, and the rewetting amount increased to 0.18 g. This indicates that the quaternized cyclodextrin composite material is the main contributing component to the antibacterial function, while also having an auxiliary improving effect on surface wetting and repeated liquid penetration.

[0056] Comparative Example 4 replaced the silane additives of this application with an equal mass of γ-aminopropyltriethoxysilane (KH-550). Its settling time was 1.66 s, the third liquid penetration time was 3.61 s, and the rewetting amount was 0.23 g, all significantly worse than Example 2; the inhibition rates against Staphylococcus aureus and Escherichia coli decreased to 82.5% and 87.6%, respectively. This indicates that although ordinary small-molecule silane coupling agents have certain interfacial effects, they are weaker than the silane additives of this application containing polysiloxane segments, aromatic structures, and Schiff base structures in terms of functional layer flexibility, inter-functional component interactions, and adhesion stability under repeated liquid action. Therefore, their overall hydrophilic durability and antibacterial retention performance are poorer.

[0057] Comparative Example 5 reduced the dry basis adhesion of the functional coating liquid from 2.0% to 0.5%. Its sinking time increased to 2.43 s, and the three liquid penetration times were 3.01 s, 3.45 s, and 3.91 s, respectively, with a rewetting amount of 0.30 g. The inhibition rates against Staphylococcus aureus and Escherichia coli were 78.8% and 75.6%, respectively, indicating that excessively low adhesion resulted in insufficient effective hydrophilic and antibacterial components on the fiber surface, making it difficult to form a continuous and stable functional layer. Therefore, the initial hydrophilicity, repeated penetration, and antibacterial properties all decreased significantly. On the other hand, the breaking strength of each comparative example remained between 3.27 and 3.35 cN / dtex, which is generally close to the 3.25 to 3.31 cN / dtex of Examples 1 to 3. This indicates that the above-mentioned single-factor changes mainly affected the fiber surface function and interfacial stability, while having a limited impact on the load-bearing structure mainly composed of the PET core layer. This result is consistent with the technical objective of this application to improve hydrophilicity and antibacterial properties while maintaining mechanical properties.

[0058] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0060] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A composite fiber for hygiene products, characterized in that, The composite fiber comprises the following raw materials in parts by weight: a core layer, a sheath layer, and a functional coating liquid. The core layer comprises 90-100 parts of polyethylene terephthalate; The skin layer comprises polyethylene and maleic anhydride-grafted polyethylene, and by weight, the skin layer consists of 94 to 98 parts of polyethylene and 2 to 6 parts of maleic anhydride-grafted polyethylene. The functional coating liquid comprises the following components: 1-2 parts of quaternized cyclodextrin composite material; 1-3 parts of silane additive; 2-4 parts polyethylene glycol; Glycerin 0.1-0.5 parts; Nonionic surfactant: 0.1–0.3 parts; 15-25 parts ethanol; 75-85 parts deionized water.

2. The composite fiber for hygiene products according to claim 1, characterized in that, The preparation method of the silane additive is as follows: S1. Vanillin and glycerol triglycidyl ether were added to a reaction flask and heated to 100-110°C under a nitrogen atmosphere. The mixture was stirred until homogeneous. Then, 4-dimethylaminopyridine catalyst was added and the reaction was carried out under magnetic stirring for 2-4 hours. After the reaction was completed, the trialdehyde precursor was obtained. S2. Add octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane and tetramethylammonium hydroxide to the reaction flask. Under nitrogen protection, stir and heat the mixture to 90°C and react for 4 hours. Then raise the temperature to 140°C and continue the reaction for 1 hour to deactivate the catalyst. Then, use a vacuum pump to evacuate the vacuum and remove unreacted raw materials and low-boiling substances by vacuum distillation to obtain diaminopropyl-terminated polysiloxane. S3. Add trialdehyde precursor and diaminopropyl-terminated polysiloxane to N,N-dimethylformamide solvent, stir and mix, react at 65-75℃ for 6-10h, distill under reduced pressure and dry under vacuum to obtain silane additive.

3. The composite fiber for hygiene products according to claim 2, characterized in that, In step S1, the ratio of vanillin, glycerol triglycidyl ether, and 4-dimethylaminopyridine catalyst is 20.2-22.9g: 21.1-23.4g: 0.41-0.45g.

4. The composite fiber for hygiene products according to claim 2, characterized in that, In step S2, the ratio of octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and tetramethylammonium hydroxide is 24-25.8g: 24.7-25.4g: 1.31-1.36g.

5. The composite fiber for hygiene products according to claim 2, characterized in that, In step S3, the trialdehyde precursor and diaminopropyl-terminated polysiloxane are mixed and reacted to achieve a molar ratio of aldehyde to amino groups of 1:

1.

6. A method for preparing composite fibers for hygiene products as described in any one of claims 1-5, characterized in that, The method for preparing the composite fiber for hygiene products is as follows: A1. Polyethylene terephthalate is vacuum dried at 120-140℃ for 4-6 hours to obtain the core layer material; polyethylene and maleic anhydride-grafted polyethylene are dried at 60-80℃ for 2-4 hours according to the weight ratio, and then mixed at 500-800r / min for 10-20 minutes to obtain the skin layer material. A2. The core material and the sheath material are fed into a bicomponent melt spinning device, wherein the melting temperature of the core material is 270-285°C and the melting temperature of the sheath material is 180-210°C. They are then transported by a metering pump to a core-sheath bicomponent spinning assembly for compounding and extrusion through a spinneret. The extruded material is then cooled and shaped at 18-25°C to obtain core-sheath nascent fiber. A3. The core-sheath type nascent fiber is stretched by 2.5 to 3.5 times at 70 to 90°C, and then heat-set at 100 to 120°C to obtain a core-sheath type bicomponent matrix fiber. A4. Add the quaternized cyclodextrin composite material, silane additive, polyethylene glycol, glycerol and nonionic surfactant to a mixed solvent composed of ethanol and deionized water according to the weight parts, stir at 600-1000 r / min for 20-40 min, and then ultrasonically disperse at 200-400 W for 15-30 min to obtain a uniform functional coating liquid. A5. The functional coating liquid is uniformly coated onto the surface of the core-sheath bicomponent matrix fiber, dried at 60-80°C for 3-8 minutes, then heat-treated at 105-120°C for 1-3 minutes, and cooled to obtain composite fiber for hygiene products.

7. The method for preparing composite fibers for hygiene products according to claim 6, characterized in that, In step A3, the setting time is 60-90 seconds.

8. The method for preparing composite fibers for hygiene products according to claim 6, characterized in that, In step A5, the dry basis adhesion amount of the functional coating liquid is 1.0 to 3.0% of the mass of the core-sheath type bicomponent matrix fiber.

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